Cessna T-37 “Tweet”
Stephen Ruby, aviation writer EAA #406241
6000 pound Dog Whistle:
The Cessna Aircraft Company of Wichita, Kansas provided the United States Army during World War II and the Korean War with utility, light transport, and observation aircraft, particularly the “O-1 Bird Dog” series.
In the spring of 1952 the United States Air Force (USAF) issued a request for proposals for a “Trainer Experimental (TX)” program, specifying a lightweight two-seat basic trainer for introducing USAF cadets to jet aircraft.
The XT-37, circa 1954.
Cessna responded to the TX request with a twin-jet design with side-by-side seating. The USAF liked the Cessna design, which was given the company designation of “Model 318”, and the side-by-side seating since it let the student and instructor interact more closely than with tandem seating. In the spring of 1954, the USAF awarded Cessna a contract for three prototypes of the Model 318, and a contract for a single static test aircraft. The Air Force designated the type as XT-37.
The XT-37 had a low straight wing, with the engines buried in the wing roots, a clamshell-type canopy hinged to open vertically to the rear, a control layout similar to that of contemporary operational USAF aircraft, ejection seats, and tricycle landing gear with a wide track of 4.3 m (14 ft). It first flew on October 12, 1954.
The wide track and a steerable nose wheel made the aircraft easy to handle on the ground, and the short landing gear avoided the need for access ladders and service stands. The aircraft was designed to be simple to maintain, with more than a hundred access panels and doors. An experienced ground crew could change an engine in about a half hour.
The XT-37 was aerodynamically clean, so much so that an air brake was fitted behind the nose wheel door to help reduce speed for landing. Since the short landing gear placed the engine air intakes close to the ground, screens pivoted over the intakes from underneath when the landing gear was extended, to prevent foreign object damage.
The XT-37 was fitted with two Continental-Teledyne J69-T-9 turbojet engines, French Turbomeca Marboré engines built under license, with 920 lbf (4.1 kN) thrust each. The engines had thrust attenuators to allow them to remain spooled-up (i.e. rotating at speeds above idle) during landing approach, permitting shorter landings while still allowing the aircraft to easily make another “go-round” in case something went wrong. Empty weight of the XT-37 was 2.27 tones (5,000 lb).
Tests showed the XT-37 had a maximum speed of 628 km/h (390 mph) at altitude, with a range of 1,505 km (935 mi). The aircraft was unpressurized, and so limited to a ceiling of 7.6 km (25,000 ft) by USAF regulations.
The initial prototype crashed during spin tests. Later prototypes had new features to improve handling, including long strakes along the nose, and an extensively redesigned and enlarged tail. After these modifications the USAF found the aircraft acceptable to their needs, and ordered it into production as the T-37A. Production aircraft remained tricky in recovering from a spin; the recovery procedure was complex compared with most aircraft.
The T-37A was delivered to the U.S. Air Force beginning in June 1956. The USAF began cadet training in the T-37A during 1957. The first T-37B was delivered in 1959. Instructors and students considered the T-37A a pleasant aircraft to fly. It handled well and was agile and responsive, though it was definitely not overpowered. It was capable of all traditional aerobatic maneuvers. Students intentionally placed the aircraft into a spin as part of their pilot training.
The Air Force made several attempts to replace the T-37 (including the T-46), but it remained in service with the USAF until it was phased out in favor of the Beechcraft T-6A Texan II between 2001 and 2009. The T-6 is a turboprop aircraft with more power, better fuel efficiency and more modern avionics than the Tweet.
The final USAF student training sortie by a T-37B aircraft in the Air Education and Training Command (AETC) took place on 17 June 2009. The last USAF operator of the T-37B, the 80th Flying Training Wing (80 FTW), flew the sortie from its home station at Sheppard AFB, Texas. The last T-37B was officially retired from active USAF service on 31 July 2009.
Stephen Ruby, aviation writer EAA #406241